Over the past decade or so, the drinking habits of Americans have undergone substantial change, as evidenced by the reduction in the consumption of alcoholic beverages over the past few years. From 1980 to 1987, beer consumption decreased 7 percent, wine consumption decreased 14 percent, and distilled spirits consumption decreased 23 percent. (New York Times, Mar. 15, 1989, page A1).
According to published sources, the reasons for the decline are numerous. There was a federal excise tax increase on distilled spirits in 1985, and there were numerous state excise tax increases in the 1980's, all of which increased the effective price to consumers.
There is an increased health consciousness on the part of Americans. They exercise more and moderate many activities in their lives, including alcohol consumption.
Also, there are numerous reports of what appears to be an increased social awareness as to the dangers of immoderate drinking. The efforts of concerned citizens, as well as heightened law enforcement activity aimed at curbing driving under the influence, has had a profound influence on our social mores. Today the seriousness of driving while impaired is more fully recognized.
Being socially responsible, as well as commercially affected by these trends, the producers of alcoholic beverages have adopted numerous strategies in conformance with these perceived new attitudes, including the introduction of products of reduced alcohol content. A wide variety of alcohol reduced products, namely beers and wines, are now available.
Low alcohol beers (a/k/a light beers) are especially popular. They have been marketed since the mid 1970's and have attracted a substantial share of the beer market. Virtually every major brewery now markets its own light beer. The reduced alcohol wines that have been marketed for some period of time have largely not been successful, most probably due to poor taste. New, allegedly improved reduced alcohol wines, however, have been recently introduced, so it is still too early to gauge the commercial success of this category.
Until now, there has only been attempt at producing a distilled spirit with a reduced alcohol content by dilution, which dramatically alters the flavor profile. The unavailability of reduced alcohol, but not diluted, distilled spirits leaves a substantial void in the market place. Many people would prefer a mixed drink over a wine or a beer, but there are no distilled spirits of lowered alcohol available having the flavor of their higher proof counterparts. Of course, they can request that their drink be mixed with less liquor and more mixer, but this is generally unacceptable to the consumer, since the distilled spirit is an important flavor constituent. Adding less spirits adversely alters the taste of the drink, as would be the case with a distilled spirit diluted with too much water. It is clear, therefore, that the best solution to this problem is to make available to the public distilled spirits which have a reduced alcohol content, while retaining all of the flavor and essences (i.e. the organoleptic properties) of their full strength derivatives.
Heretofore effective alcohol reduction methods have been proposed for beer and wine; but such methods have not been provided for the reduction of alcohol and of distilled spirits. Most traditional types of U.S. spirits products, as defined under Federal and State regulations, have an alcohol content of 40 percent by volume (80 proof) or greater.
When reducing the alcohol content of spirits, a method must be devised wherein the alcohol content can be reduced without destroying or otherwise adversely altering the flavor and organoleptic properties of the reduced alcohol spirit. Distillation or other processes employing heat are unacceptable for this task. Exposing a spirit to heat produces a reduced alcohol product which has significant negative differences from the flavor and other organoleptic properties of the original product. Accordingly, any process for reducing the alcohol content of distilled spirits, if it is to be organoleptically acceptable and commercially effective, cannot utilize heat.
One such method used to separate components of a mixture which does not rely upon heat is reverse osmosis. The prior art discloses processes whereby the alcohol content of alcoholic beverage is reduced by means of reverse osmosis. For example, U.S. Pat. No. 4,499,117 discloses a process whereby the natural alcohol containing liquid is subjected to ultrafiltering at low pressure, using a filter whose molecular weight separation threshold is 10,000, which forms a retentate and filtrate. The filtrate is then subjected to reverse osmosis under pressure using a filter whose molecular weight separation threshold is 250 to form a second retentate and filtrate, and then evaporating the filtrate by vacuum distillation at low temperature, forming a third retentate composed of molecules with molecular weight less than 250, and a distillate which is alcohol, and then mixing the aforementioned components to form the reduced alcohol beverage. This is not an efficient process, since it requires three successive steps of physical fractionation and, therefore, is a time consuming process. Furthermore, vacuum distillation may cause the removal of volatile components of the spirit which are responsible for the flavor and organoleptic properties that provide its essential character.
In U.S. Pat. No. 4,532,140, a process is disclosed wherein an alcohol containing liquid is subjected to either ultrafiltration or reverse osmosis, creating a concentrate and permeate. The permeate is then subjected to a second reverse osmosis procedure, whereby the permeate contains water as opposed to alcohol. The concentrates from the two passes are then combined. This process is limited solely to the alcohol reduction of wines and beers (must and worts). Also, this process required multiple fractionations in order to achieve the desired result. It therefore is not an efficient process.
In U.S. Pat. No. 4,612,196, a process is disclosed for reducing the alcohol content of a malt beverage by reverse osmosis, utilizing a thin film composite membrane having a polyamide active barrier on a microporous polysulfone support. This membrane, having chloride ion rejection capabilities of 98% for a 5000 mg/l solution of NaCl at 15.degree. C. and 580 psi, retains the volatiles and other flavor constituents of the beer while allowing 25 to 30% of the alcohol to pass through the membrane as permeate. The process is entended to operate at pressures between 500 and 900 psi. The process described in this patent would not apply to distilled spirits.
In U.S. Pat. No. 4,717,482, a reverse osmosis technique is disclosed utilizing a semipermeable membrane with a chloride ion rejection rate greater than 80% at a net pressure of 400 psi. The membrane separates the alcohol containing feed into a retentate and permeate, the latter comprised of mainly alcohol and water. The retentate, also containing alcohol, is recycled back to the reverse osmosis system where it is admixed with the fresh feed and water. This process is limited to removal of alcohol from beer or wine. It utilizes a recycle process wherein 80 to 99 percent of the retentate is recycled back into the system. Since a relatively small fraction of the retentate is drawn off, constituting the reduced alcohol beverage, this process is extremely inefficient.
In U.S. Pat. No. 4,788,688, a process is disclosed wherein the ethanol content of a distilled spirit (and none of the water contained therein) is removed. The process relies solely upon diffusion across a semi-permeable membrane as the means by which alcohol content is reduced. The membranes chosen are generally permeable to water and ethanol. However, because ethanol extraction fluids are utilized which do not permit the passage of water through the membrane, only ethanol can pass therethrough. These ethanol extraction fluids can be either of two kinds: either a water immiscible fluid in which ethanol is soluble; or an aqueous solution of an osmotic agent exhibiting an osmotic pressure equivalent to or approximately that of the ethanol containing feed stream. This process does not adequately solve the problem of removing the alcohol content of a distilled spirit because it is an inefficient process and a difficult operation to maintain. Alcohol reduction depends solely upon the difference in ethanol concentration across the semi-permeable membrane, i.e.--the diffusional driving force. The rate of mass transfer may be controlled by varying the flow rate of the extraction fluid. However, the flow rates of the alcoholic beverage must remain low in order to insure adequate retention time inside the reactor vessel. Because the flow rates must be limited, it is questionable whether utilizing this process to reduce the alcohol content of a batch quantity of distilled spirits is a commercially viable operation. In any event, the process does not utilize pressure as a means for effecting the removal of alcohol. Indeed, pressure cannot be used because the use thereof would probably cause broken fibers or membrane defects that would contaminate the feed stock with the extraction fluid, ruining the feedstock and rendering it unconsumable and of no commercial value.